“Eсть аврора” (yest avrora – there is the aurora) our bus driver says, pointing out of the front window as we arrive high on a hill on the outskirts of Murmansk where we have escaped the city lights. It is January 4, 2018 and our third night north of the Arctic circle in search of the Northern Lights. We pile off the bus into the deep snow and stare to the north at what might possibly be a faint green glow low in the sky. So, this is it? This is what we have come from New Zealand, Australia, the UK, USA, Spain, South Africa – from countries around the world – to see? A faint green glow? I am not happy with this. I am the Golden Eagle Luxury Trains “In Search of the Northern Lights” astronomer, and although it is unspoken, it is clear to all that I am responsible for providing a good aurora, not just this faint green glow. In Norse mythology, when the Valkyries are on the hunt for the slain to take them to Valhalla, the light flickering off their armour creates the aurorae. Tonight, it seems the hunt is not going well.
I have explained to the passengers that the Sun provides the raw material for an aurora in the electrons and protons that stream off its surface in the “solar wind”. Those particles are captured by the Earth’s magnetic field, but the wind also “blows” the magnetic field into a long tail extending out of the Earth’s night side, with magnetic field “lines” waving around in the wind from the Sun. Occasionally, the magnetic field lines can “reconnect” (a kind of magnetic short-circuit), and the resultant “geomagnetic storm” releases lots of energy that accelerates the electrons to high speed and dumps them low into the Earth’s far northern and southern atmosphere where they cause the air to glow to produce sometimes spectacular auroral displays. Because this energy is primarily dumped into the night side of the Earth’s atmosphere, the best time to see the aurora is around local midnight, even though we are so far north that the sun never rises in January and, apart for a few hours of twilight around noon, it is dark all the time. Midnight is still a better time to look.
So, on this night we have had another wonderful evening banquet in the dining car on the Golden Eagle, parked at the Murmansk rail station, after which I can see that the sky is partially clear and some stars are visible. The passengers ask me what the chances are of seeing the aurora tonight, and I tell them that the space weather prediction from the NOAA (the USA’s National Oceanographic and Atmospheric Administration) is for low probability tonight. “The chance of our seeing the aurora tonight is less than 20%, but the chance is never zero”, I say. So, we change from dinner clothes to our Arctic coats, hats, boots – it is -9 C outside – and board our bus to head out of town where the sky is darker.
There on the hill above town some local people have also come out to look for the aurora. But with only the faint green glow, I decide to talk about the stars we can see in the clear sky. Few in the group had ever seen the sky from so far north, and way up there near the north pole, the sky really is different from the lower latitudes where all of us live. If you stood on the north polar icecap in winter, you could watch the stars go around in circles parallel to the horizon – never rising, never setting – and Polaris, the pole star would be permanently at the zenith. At 90 degrees north latitude, the pole star is 90 degrees above the horizon. In fact, this is a general rule the comes simply from geometry: in the northern hemisphere, the height of the pole star above the horizon is equal to your latitude. Sailors have used this fact for millennia to determine their latitude at sea.
From our hill above Murmansk at latitude 69 degrees north, the pole star was 69 degrees high directly to the north, or only 21 degrees from the zenith. And most of the stars went around the sky, neither rising or setting, although they did get higher and lower. That was true of the moon, too. On January 2 we had seen the full moon from Kirkenes in Norway, as it travelled around the sky, only setting for a few hours around local noon. On our hill outside Murmansk we could see the Big Bear and Little Bear, Ursa Major and Ursa Minor, to the north in the faint glow of the aurora; to the south were Orion with the bright red supergiant star, Betelgeuse, and Taurus with the Pleiades star cluster.
I was pointing out the stars and constellations and talking about the stupendous distances to the stars and some amazing facts about them. For example, Betelgeuse is so big that, if it were where the Sun is in our solar system, Mercury, Venus, Earth, Mars and even Jupiter would be inside the star. Betelgeuse is a prime candidate to go supernova sometime in the next few million years (maybe even tomorrow!). I also told the story of what really happened at Roswell, New Mexico, in July, 1947, shortly after American private pilot Kenneth Arnold had been misquoted in the press as seeing “flying saucers”. (He said he saw mysterious objects skimming erratically across the sky, as a saucer would skim if you threw it across water. Arnold actually said the objects were boomerang shaped, but with the misquote in the newspaper, it has been flying saucers ever since). And since you ask, no, there is no credible evidence that Earth is being, or ever has been, visited by intelligent creatures from elsewhere in the universe. For the full story on Roswell, you will need to join me on a future Golden Eagle journey. Ask me after dinner, and I will tell you the story.
We were tired after a long, interesting day of travel, and a typical outstanding Golden Eagle dinner with fine wine. It was cold. Actually, for just standing around in the dark, it was very cold. The stars were beautiful, and my stories seemed to be entertaining everyone while we stargazed, but then a murmur arose and you could hear the message passing from person to person: The auroral oval was a bright green band now and moving much higher in the northern sky. Minutes later to the northwest, the goddess of the dawn, Aurora, heard our pleas, and a great, green curtain with a red-tinged top shimmered and waved brilliantly in the sky. This is what we had come for! Now the bus driver was really right: “Eсть аврора!”
Ten minutes later the sky display faded as quickly as it had come, giving us the perfect cue to board the warm bus and head back to the Golden Eagle for a night tucked into our compartments as the train journeyed south to Petrozavodsk. Everyone was happy – especially me! Previously, I had been responsible for there being at best a poor, faint aurora. Now I was given credit for having produced a beautiful, bright one, a “good” aurora. Such is the responsibility and luck of being an astronomer.
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